by Rick Jervis, USA TODAY

by Rick Jervis, USA TODAY

The FBI investigation into former CIA Director David Petraeus' extramarital affair with Paula Broadwell found no apparent threat to national security, so there was no reason to notify President Obama or Congress, Attorney General Eric Holder said Thursday.

"We conducted that investigation the way we normally conduct criminal investigations," Holder said at a press conference in New Orleans, his first public comments on the matter. "We do not share outside the Justice Department, outside the FBI, the facts of ongoing investigations."

"We made the determination as we were going through the matter that there was not a threat to national security," Holder said. "Had we made the determination that a threat to national security existed, we would of course have made that known to the president and also to the appropriate members on the Hill."

Only after Broadwell was interviewed Nov. 2 was the decision made to alert the White House.

"When we got to that point, where we thought it was appropriate to share the information, we did so," he said.

Petraeus was cleared of mishandling classified information. But the FBI found that Broadwell, his biographer and an Army reservist, had classified material on her computer and remains under investigation, according to news reports.

Also Thursday, the CIA announced that the agency's inspector general had opened an "exploratory" investigation of Petraeus.